124 BEITISH DESMIDIACEJ:. 



processes on the polar lobe, was first mentioned by Lundell 

 (' Desm. Suec/ 1871, p. 15). The figure we give of this form 

 also shows the lobulation of typical M. Mahabuleshwarensis on 

 one side of the semicell and that of the var. Wallichii on the 

 other. This in itself is conclusive proof that the Desmid 

 originally described as Micrasterias Wallichii is only a variety 

 (in some localities well established) of M. Mahabulesliwarensis. 



SPECIES TO BE INQUIRED INTO. 



Micrasterias cornuta Benn. (PL LI, fig. 1.) 



Micrasterias cornuta Benn. Freshw. Alg. Eng. Lake Distr. 1886, p. 7, t. 1, 

 f. 6 ; Cooke, Brit. Desm. 1886, p. 57, t. 23 [after Bennett] ; De Toni, 

 Syll. Alg. 1889, p. 1156. 



Helierella Bennettii Kuntze, Revis. gen. plant. 1891, p. 898. 



Cells large, deeply constricted, sinus narrowly linear ; 

 semicells with a large projecting polar lobe, the angles 

 of which are bluntly rounded and the apex deeply 

 concave ; lateral lobes (according to Bennett's figure) 

 three on each side, separated by two narrow and not 

 very deep primary incisions, each lobe divided by a 

 narrow secondary incision into two lobules, each lobule 

 rounded-truncate with a median emargination or 

 incision. 



Length 355/u,; breadth 305 //,. 



ENGLAND. Stream between Codale and Stickle 

 Tarns, Westmoreland, at an elevation of about 1,800 ft. 

 (Bennett). 



We do not think Bennett's figure of this Micrasterias, of 

 which we give a copy,, is a correct one. No known species of 

 the genus possesses lateral incisions of the nature he has 

 figured. Had the lower of the two deepest lateral incisions 

 been made much deeper, this would have given a lobulation 

 somewhat comparable with that of M. rotata. Taking into 

 consideration the great inaccuracy of most of Bennett's pub- 

 lished figures, we should imagine that the Desmid he had 

 under observation when he made his drawing was a large, 

 and possibly an abnormal form of M. rotata. 



